Well bridging apparatus having a detachable setting means

ABSTRACT

An illustrative embodiment of the present invention in through tubing bridge plugs includes a body member carrying an expansible bridging element, a pump and receptacle assembly releasably coupled to the body member and adapted to contain a cementitious material that can be displaced from the receptacle to expand the bridging element, a vent passage through the body member to enable fluid movement within the well bore without disturbing the cementitious material as it hardens, and valve means automatically operable after a pre-selected time delay for closing off the vent passageway.

United States Patent Owens [451 Mar. 21, 1972 54 WELL BRIDGING APPARATUS HAVING 2,681,114 6/1954 Conrad ..l66/l8l x A DETACHABLE SETTING MEANS 2,695,065 11/ 1954 Baker et al... .166/ 181 X 3,460,625 8/1969 Hart et al..... ..l66/l87 X [721 Invent Owens 3,524,501 8/1970 Armstrong ..l66/l82 [73] Assignee: Schlumberger Technology Corporation,

New York, NY, Primary Examiner-David H. Brown Attorney-Ernest R. Archambeau, .Ir., Donald H. Fidler, [22] filed 1970 David L Moseley, Edward M. Roney and William R. Sherman 21 Appl. No.: 38,621

[57] ABSTRACT Related US. Application Data An lllustrative embodiment [of the present mvennon in Dlvlslon of 819,515 P 1969' through tubing bridge plugs includes a body member carrying 35561215' an expansible bridging element, a pump and receptacle assembly releasably coupled to the body member and adapted to contain a cementitious material that can be displaced from the n receptacle to expand the bridging element, a vent passage [58] Field oi Search ..l66/l8l,l82,l87,123,125 through the y member to enable fluid movement within the well bore without disturbing the cementitious material as it [56] References Cited hardens, and valve means automatically operable after a pre- UNITED STATES PATENTS selected time delay for closing off the vent passageway.

2,189,937 2/1940 Broyles ..l66/182 X 3 Claims, 11 Drawing Figures Patented March 21, 1972 3,650,325

4 Sheets-Sheet 1 ATTORNEY Patented March 21,1972 3,650,325

4 Sheets-Sheet 5 FIGS Navy! 6. Owens INVENTOR ATTORNEY WELL BRIDGING APPARATUS HAVING A DETAC'I-IABLE SETTING MEANS This is a division of application Ser. No. 819,515, filed Apr. 22, I969.

The present invention relates generally to plugs adapted to form a pressure bridge in a well conduit (either caused or open hole), and more specifically to a new and improved thrutubing bridge plug apparatus having a vent passage which is automatically closed after a pre-s elected time lapse.

It is often desirable to form a pressure bridge or plug in a well conduit below the lower end ofa relatively small diameter pipe or .tubing string extending therein. This can be accomplished by utilizing one of the various embodiments of thrutubing bridge plugs disclosed in the copending Han et al. application Ser. No. 631,091, entitled Methods and Apparatus for Bridging a Well Conduit filed Apr. 14, 1967, and assigned to an assignor of the present invention. Basically these devices are adapted to be run into the well on electrical cable or wireline and are comprised ofa central support carrying an inflatable packing element and coupled to a receptacle containing an initially fluent medium, such as cement slurry, which is capable of subsequently hardening. The device is sized and arranged to be lowered into the well through a tubing string and to a setting point below the lower end thereof, whereupon a positive displacement pump can be actuated upon signal from the surface to expand the packing element so as to provide a.

bridge across the well conduit. A column of cement slurry is also deposited on top of the bridge and allowed to harden to provide a substantial cement plug which functions to prevent fluid flow in either longitudinal direction. well As fully described in the aforementioned Hart et al. application, a vent passage is provided in the support extending between locations in communication with the well bore above and below the packing element to enable fluids moving within the casing to pass through the cement column without disturbing it during the hardening process, Otherwise, such fluid movement can cause channels through the cement which remain after it hardens and destroy the ability of the plug to hold pressure. After the cement is hardened, the vent passageway is closed by either lowering a valve element from the surface and positioning it to close off the passageway, or by manipulating from the surface a valve element in the tool to a condition closing the passageway. Although a thru-tubing bridge plug apparatus in accordance with the concepts disclosed in the Hart et al. application has been found to be quite satisfactory, the valve closing operation requires either a subsequent trip into the wel to close the valve, or requires leaving the pump and receptacle in the well for the period of time necessary for the cement column to harden, Both procedures involve a certain amount of time delay that ties up men and equipment at the well site with attendant expense.

It is accordingly the primary object of the present invention to provide new and improved apparatus of the type described above, and wherein the vent passageway is automatically closed after a pre-selected time lapse calculated to enable the cement column to harden.

In order that the bridge plug setting operation be carried out with maximum dispatch, it is desirable to be able to withdraw the pump and cement receptacle from the wall bore soon after setting the plug. In the past, a certain amount of delay was involved to enable the cement within and on top of the packer to harden so that an upward pull on the wireline could be used to release the pump and receptacle. Otherwise, the plug was not sufficiently anchored to permit such upward force to be applied.

It is accordingly a further object of the present invention to provide a new and improved thru-tubing bridge plug apparatus having a releasable connection between the bridge plug and the cement receptacle which is automatically released after the pump and receptacle have performed their functions so that they can be immediately withdrawn from the well without disturbing the set condition or position of the bridge plug.

These and other objects are attained in accordance with the present invention by the provision of an apparatus including an elongated body member carrying an inflatable packer means that is adapted for a wide range of expansion upon inflation. Releasably coupled to the body member is a receptacle which contains cement slurry or the like, and a pump device that can be operated remotely or from the earth's surface. The pump functions to positively displace sufficient cement slurry into the packer means to expand it into engagement with the surrounding well conduit wall, whereupon the balance of the slurry contained within the receptacle is deposited on top of the packer. A latch connection between the receptacle and the body member is automatically released when the pump has displaced all the cement slurry from the receptacle so that the pump and receptacle can be withdrawn to the surface without waiting for a hardened condition of the cement to transpire.

A passageway extends from a location in communication with the well bore below the packer means to a location in communication with the well bore above the column to provide a flow course through which well fluids can pass temporarily without disturbing the cement as it hardens. A normally open valve means is adapted to close off the passageway, and is operated to do so by a means which is restrained, however, by a time delay. Accordingly, the valve means cannot move into a condition closing off the passageway until the expiration of a pre-selected time interval which is sufficient to enable the cement to harden and provide an effective plug.

The invention has other objects and advantages which will become apparent in connection with the following detailed description. The novel features of the present invention being set forth with particularly in the appended claims, the present invention, both as to its organization and manner of operation, may best be understood by way of illustration and example of an embodiment thereof when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic view of an apparatus incorporating the principles of the present invention being lowered into a well through tubing:

FIGS. 2A and 2B are longitudinal sectional views to illustrate the general structural details of the apparatus shown in FIG. 1. FIG. 2B forming a lower continuation of FIG. 2A,

FIG. 3 is a detailed cross-sectional view of the latch construction connecting the receptacle to the bridge plug body;

FIG. 4 is a cross section taken on line 4-4 of FIG. 3;

FIG. 5 is an enlarged sectional view of the vent valve structure, actuator, and timer mechanism;

FIG. 6 is a side view of the timer mechanism;

FIG. 7 is an isometric view of the shaft of the timer main wheel showing the release cord attached thereto;

FIG. 8 illustrates an alternate embodiment of the timer;

FIG. 9 is a sectional view of the lowerportion of the apparatus after the packing element has been expanded to provide a bridge in the well; and

FIG. 10 is a view similar to FIG. 9v but with various parts operated for depositing a column of cement on the top of the plug.

Referring initially to FIG. 1, a thru-tubing bridge plug assembly which is described to illustrate the principles of the present invention is shown being lowered at the end of a wireline W through a tubing string T toward a selected setting point with a well casing C below the lower end of the tubing string. The assembly includes a dump bailer actuator or pump section 10 coupled to the upper end of a positive displacement dump bailer or receptacle 11. The receptacle 1] is, in turn, releasably connected to the upper end of an elongated body member 12 which carries an inflatable packer element 13. The packer element 13 may comprise an inflatable packing sleeve or bag which is normally collapsed during lowering and which can be expanded to several times its collapsed size in order to bridge the well bore. A valve and timer assembly 14 forms the lower part of the apparatus. The entire assembly is constructed and arranged to pass downwardly through, for example, a 1 25/32 bore, and can be operated to pack off or bridge a range ofcasing sizes from 3 9% to 7 Referring now to FIG. 2A for further detail, the dump bailer actuator section 10 includes a tubular case 17 having a longitudinally extending chamber 18 therein. A piston 19 is movably received within the chamber 18, and a rod 20 connected to the piston extends downwardly through a bore 21 which opens axially into the chamber 18. The upper portion of the chamber 18v is arranged to receive a suitable hydraulic fluid, and a coil compression spring 22 is arranged in the lower portion of the chamber to urge the piston 19 and the rod 29 upwardly. Several side ports 23 in the wall of the case 17 below the piston 19 enable fluid pressures within the chamber 18 to be balanced with hydrostatic well fluid pressures as the tool is lowered into a fluid filled well bore. To permit placement of hydraulic fluid into the upper portion of the chamber 18, a one-way check valve 24 in an entry passage 25 is provided. An exit passage 26 extends from the chamber 18 to the exterior of the case 17, and has a remotely controllable valve 27 therein, such as a conventional solenoid operated valve, which normally prevents discharge of hydraulic fluid from the chamber. With this condition of parts, the piston 19 and the rod 20 cannot move upwardly under the influence of the upward force being exerted by the coil spring 22.

The piston rod 20 extends downwardly through the bore 21 to a location within a recess 30 where it can operate a latch device. The latch device includes a plurality of upwardly extending, inwardly biased spring fingers 31, which terminate in enlarged head portions 32. When the parts are in the relative positions shown in FIG. 2A, the head portions 32 are held outwardly by the rod 20 in engagement with a shoulder 33 formed by the recess 30. However, it will be appreciated that removal of the rod 20 from behind the head portions 32 will permit them to spring inwardly and out of engagement with the shoulder 33. The retention and release of the spring fingers 31 from the recess 30 controls the operation of the positive displacement dump bailer section 11.

The dump bailer section includes a cylinder 35 connected at its upper end to the control section 10: The lower end of the housing 35 is releasably connected by a latch device 36 to upper end of the body member 12. The cylinder has a bore 37 in which a weighted body 38 is movable. The weighted body 38 can take the form of an elongated tubular member having a rod 39 extending upwardly from its upper end, the rod having the previously described spring fingers 31 connected to its upper end and extending into the recess 30. A coil spring 40 can surround the rod 39 with its upper end pressing against the upper end of the bore 37 and its lower end pressing against the upper surface of the weighted body 38.

Also positioned within the bore of the cylinder 35 and spaced downwardly from the lower end of the weighted body 38 is a piston assembly 41 having an elastomer swab cup 42 or the like facing in a downward direction, The swab cup 42 defines the upper end of a fluent material chamber 43 that is adapted to contain a suitable material, such as cement slurry which has liquid or flowable properties for a predetermined length of time and which is thereafter capable of hardening or setting up to form a solid mass. The lower end portion of the housing is formed by a latch sleeve 44 having a plurality of circumferentially spaced, downwardly extending latch fingers 45 having enlarged head portions 46 which are normally received within an annular recess 47 formed in the inside wall of the upper end of the body member 12. As shown in enlarged detail in FIG. 3, the latch sleeve 44 has a reduced peripheral portion 48 which is received within the upper end portion 49 of the body member 12 and which is sealed with respect to the body member by an O-ring 50. The latch fingers 45 are formed in such a manner that they tend to resile inwardly to the extent that the head portions 46 are disengaged from the recess 47, however the head portions are retained in engaged positions by the provision of an annular support ring 52 normally located behind the head portions 46. The support ring 52 is attached to the lower end of a shifting member 53 which can consist of two L-shaped plates arranged in opposition to one another as shown in FIG. 4. The upper ends of the plates are encompassed by a cap 54 having an outwardly extending annular lip 55. A coil spring 56 is located between the lip 55 and an inwardly extending shoulder 57 on the latch sleeve 44 to maintain the support ring 52 in proper spaced relationship behind the head portions 46.

Referring again to FIGS. 2A and 2B, the body member 12 may be constituted by a two piece assembly including a tubular valve housing 60 and a packer mandrel 61 which are coupled together by screws 62 or the like. The through bore ofthe valve housing 60 is provided with a stepped diameter. An annular valve element 63 is slidably received within the housing 60, the valve element being in the form ofa sleeve piston having an annular head 64 which is sealed with respect to wall surface-65 by an Oring 66. The valve element 63 further has a tubular portion 67 extending downwardly into the small diameter bore portion 68. The annular housing space 70 below the head 64 is placed in communication with the well annulus by one or more radially extending ports 71. A shear pin 72 or the like extends through the wall of thehousing 60 and engages within a recess on the tubular portion 67 in order normally to retain the valve element 63 is the position shown in FIG. 2B.

The valve element 63 further has a central bore 73 extending throughout its length which sealing receives an enlarged portion 74 of an elongated vent tube 75. The enlarged portion 74 is sealed against the bore wall of the valve element 63 by an O-ring 76. The lower end of the vent tube 75 is seated and sealed within a counterbore 77 in the mandrel 61, whereas the upper end thereof is formed in a tee configuration to provide oppositely disposed ports 78 and 79 (FIG. 2A) that are in communication with the well bore. The outer periphery of the vent tube 75 is laterally spaced relative to the respective inner wall surfaces 73 and 81 ofthe valve element 63 and the packer mandrel 61, and the annular space thus formed is communicated with the interior of the packer element 13 by several ports 82. Thus it will be appreciated that the valve element 63 is arranged to prevent flow of the fluent material from the chamber 43 (FIG. 2A) as long as the valve element is retained in its upper position as shown in FIG. 2B. However, when the shear pin 72 fails, the valve element 63 can move downwardly to dispose the enlarged portion 74 of the vent tube 75 thereabove, thereby placing the chamber 43 in communication with the interior of the packer element 13 via the inflation passage 80 and the ports 82. Accordingly, the cement slurry can be displaced into the packing element 13 to inflate it and expand it into contact with the well casing wall.

The mandrel 61 carries the inflatable packer element 13. The packer element 13 can be formed of a suitable flexible and impervious material such as neoprene impregnated Dacron cloth. The element 13 can have longitudinal or spiral folds (not shown) therein to reduce its lateral dimensions greatly and enable it to pass through the tubing. To ensure that the element 13 remains folded during running, it can be wrapped with friction tape or the like which will break when subjected to inflation pressures. The lower end portion of the element 13 is secured by clamps or the like to a lower sliding sleeve 85 and its upper end similarly secured to an upper sliding sleeve 86. Suitable seals 87 and 88 fluidly seal between the sleeves and the mandrel 61 to prevent any fluid leakage from the bag 13. The upper sleeve 86 can be initially restrained against sliding motion relative to the mandrel 61 by the provision of resilient latch fingers 89 having inwardly extending projections 90 engaging within an external annular recess 91 in the mandrel 61. By exerting an upward pull on the mandrel 61 the that packer element 13 is in forceful contact with the well casing, the projections 90 will be cammed outwardly and disengaged to permit the mandrel to be shifted upwardly for purposes which will be more fully described hereafter.

The central opening 92 of the vent tube 75 and the mandrel bore 93 provide a vent passageway which extends from a plurality of radially extending side ports 94 located below the packer bag 13 to the upper ports 78, 79. The passageway is adapted to be closed off by a vent valve in the form of a vertically movable sleeve 95. The valve sleeve 95 is normally positioned below the side ports 94, and has seal elements 96 and 97 which will seal above and below the ports 94 when the valve sleeve is moved to an upper position spanning the side ports. Upward movement of the valve sleeve 95 is limited by a downwardly facing shoulder 98 on the mandrel 61.

A coil spring 100 is positioned within the bore 93 of the mandrel 61. The upper end of the spring 100 is anchored by a suitable means such as a transversely extending pin 101. A lower straight portion 102 of the spring extends downwardly through the bore of the valve sleeve 95 and is provided with a hook 103 at its lower end. A washer 104 or the like is loosely slidable on the spring portion 102, and the hook and washer are sized to engage the lower end surface of the valve sleeve 95.

A timer housing 106 is'secured to the lower end of the packer mandrel 61. The housing 106 provides a stepped diameter chamber 107, and the lower end of the housing is closed by a removable cap 108. A timer mechanism 109 is located within the lower portion of the chamber 107 and has a circular plate 110 which is sealed against the shoulder 111 by a packing washer 112. If desired, the void space below the shoulder 111 can be filled with a suitable lubricating fluid.

As shown in enlarged detail in FIGS. 5-7, the timer mechanism 109 includes a clockwork gear train 113 mounted between fixed side plates 114 and 115. The motion of the gear train 113 is controlled by an escapement 116 and balance 117. The main wheel 118 has its shaft 119 provided with a diametrically extending hole 120. The end of a release cord 122 is wrapped several turns around the shaft 119 and is provided with a ferrule 123 or the like which is inserted through the hole 120 as shown in FIG. 7. The release cord 122 extends through an aperture 124 in the end plate 110 as shown in FIG. 6 and has an eye 125 which is received on the hook 103 of the spring 100. With the coil spring 100 extended to an energy storing condition, it will be appreciated that the spring force will apply torque to the shaft 119 of the main wheel 118 ofthe timer assembly 109. The gear train 113, escapement 116 and balance 117 will allow the release cord 122 to unwind from the shaft 119 at a high controlled rate. Once the cord 122 is unwound and the ferrule 123 reaches a position in substantial vertical alignment with the longitudinal axis of the timer housing 106, the ferrule will release from the shaft hole 120 and enable the lower portion 102 of the spring to travel upwardly. The hook 103 and washer 104 will engage the lower end surface of the valve sleeve 95, thereby shifting the valve sleeve upwardly against the stop shoulder 98 and in spanning relationship to the side ports 94. In this condition, the valve sleeve 95 functions to block fluid through the vent passageway.

An alternative embodiment of a timer mechanism is shown in cutaway view in FIG. 8. In this embodiment, the motion control for the gear train 113 is provided by a paddle wheel 126. The paddle wheel 126 replaces the balance in the first described embodiment, and is coupled to the gear train by fifth wheel 127 which replaces the escapement. The fluid friction resisting turning motion of the paddle wheel 126 provides the restraining influence which causes the gear train 113 to enable unwinding of the release cord 122 as previously described at a highly controllable rate. Consequently, the timer mechanism is used to delay the valve closing event for a preselected time.

OPERATION In operation, the tool is prepared for lowering into the well by filling the control chamber 18 above the release piston 19 with a suitable hydraulic fluid so that the rod 20 extends into the recess 30. The weighted body 38 is forced upwardly, compressing the coil spring 40 until the latch heads 32 are inserted into the recess 30, thereby forcing the rod 20 upwardly until heads fully enter the recess 30. The spring fingers 31 cause the heads 32 to shift outwardly over the shoulder 33, and the rod 20 then shifts downwardly to retain the latch. The coil spring exerts downward force on the weighted body 38. The dump bailer assembly 11 is latched to the body member 12 by inserting the latch sleeve 44 within the upper portion 49 and positioning the support ring 52 behind the latch fingers so that the head portion 46 are held outwardly in engagement with the recess 47. The valve element 63 is secured in its upper or closed position by the shear screw 72, and the chamber 43 within the bailer section 11 is filled with predetermined volume of cementitious material. The vent valve closing spring 100 is extended and the hook 103 connected to the eye 125 of the release cord 122 having its end wrapped several turns around the shaft 119 of the main wheel 118 of the timer mechanism 109. The delay involved in closing of the vent passageway is a function of the length of the release cord wrapped around the shaft 119, and the valve closing event can be preselected to occur at a later time, for example, 18 hours. The vent valve 95 is located in its lower position where the side ports 94 are open.

The tool is then lowered downwardly into the well on the electrical cable W through the tubing T and to a selected setting point within the well casing C below the lowermost end of the tubing. At setting depth, an electrical signal set through the cable W from the surface will open the solenoid valve 27 in the pump section 10 so the hydraulic fluid can exit from the chamber 18. The force exerted by the spring 22 will move the piston 19 and the rod 20 upwardly, forcing fluid from the chamber 18. As the rod 20 moves upwardly, the spring fingers 31 are freed to flex inwardly and release from the recess 30, thereby releasing the weighted body 38.

The force of the spring 40 acts to accelerate the weighted body 38 downwardly so that it strikes the piston assembly 41 in a violent manner. This creates a substantial pressure wave in the cement slurry which impinges upon the upper face of the valve element 63, thereby generating a substantial force which functions to shear off the retaining screw 72. Release of the retaining screw 72 permits the valve element 63 to move downwardly to its lower position shown in FIG. 9 so that the cement slurry can flow through the inflation passage 80, the ports 82 and into the interior of the packer element 13.

The weighted body 38 will rest on the piston assembly 41 and tend to gravitate downwardly, thereby forcing the swab cup 42 downwardly and generating pressure within the chamber 43 to displace the slurry into the element 13. It will be appreciated that the inflation pressure is a function of the weight of the body 38 and the cross-sectional area of the swab" cup 42. The weighted body 38 can be constructed of suitable heavy or dense metal such as tungsten or lead and be sized so that a suitable inflation pressure, such as, for example,

15-25 p.s.i. can be developed within the packer element 13 to expand it into forceful and sealing contact with the well conduit wall as shown in FIG. 9. Since the upper sleeve 86 is attached to the mandrel 61 by the latch fingers 89 and projections 90, the lower sleeve will slide upwardly along the mandrel during expansion of the packer element 13.

After the packer element 13 is fully inflated, it forms, in effect, a platform or bridge in the well bore upon which additional cement slurry can be deposited. This can be accomplished by manipulation of the tool including an upward pull on the cable W. The friction between the packer element 13 and the casing C will enable an upward force on the mandrel 61 to cause release of the projections so that the mandrel can be shifted upwardly relative to the packer element 13, thereby exposing the inflation ports 82 to the well annulus above the bag as shown in FIG. 10. Movement of the inflation ports above the seals 88 on the sleeve 86 traps the inflation pressure within the expanded packing element and permits dumping the remainder of the cement slurry within the chamber 43 on top of the element 13. When the swab cup 42 reaches the lower end of the chamber 43, it will engage the cap 54 and causing the shifting member 53 to move the support ring 52 downwardly and out from behind the latch fingers 45. The fingers 45 can then resile inwardly so that the head portions 46 release from the latch recess 47. Accordingly, the dump bailer and actuator sections 11 and are automatically released and can be immediately withdrawn from the well. Additional dump bailer runs can be made as desired to increase the overall length of the cement plug.

During the time that the cement is hardening, the vent passageway formed by the vent tube and mandrel bores 92 and 93 remains in open condition as shown in FIG. 9 so that any produced fluids entering the casing C from below the packer element 13 can pass upwardly therethrough and enter the well annulus above the plug through the upper ports 78,79. Accordingly, it will be appreciated that such fluids will have no tendency to form channels either around the packer element 13 or through the material on top of it, which disturbances may otherwise destroy the effectiveness of the plug to hold pressure. The timer mechanism 109 has, of course, been running ever since the same was initiated at the top of the well bore. At the end of the preselected delay time, the release cord 122 will have unwound from the shaft 119 so that the ferrule 123 will release as previously described. The spring 100 will then force the valve sleeve 95 upwardly to closed position to block all vertical movement of fluids within the well casing C.

A new and improved apparatus has been disclosed for effectively plugging a well conduit. In accordance with the present invention, the plug can be lowered through tubing and then set or formed in casing or open hole without removing the smaller tubing from the well. The invention is arranged in a manner for controllably bypassing or venting fluid flow while the plug is forming to prevent disturbance of the plug. After a preselected time lapse, the vent passage is automatically closed off without the need for further manipulations or operations from the top of the well bore.

Since certain changes and modifications may be made in the disclosed embodiment of the invention without departing from the concepts involved, it is the aim of the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the present invention.

I claim:

1. In a well tool for bridging a well bore: a body member carrying an inflatable packing element; a receptacle containing a fluent medium; passage means communicating said receptacle with the interior of said pacing means; pump means including a piston member movable downwardly in said receptacle for forcing said fluent medium through said passage means and into the interior of said packing means to inflate said packing means; latch means between said receptacle and said body member for releasably coupling said receptacle to said body member; and release means cooperating between said piston member and said latch means for releasing said latch means after said piston means has forced all said fluent medium from said receptacle.

2. The well tool of claim 1 wherein said latch means includes laterally biased spring fingers on said receptacle having head portions engageable with an annular recess on said body member, and support means for retaining said head portion engaged with said recess; said release means including a shifting member coupled to said support means, said shifting member being positioned for engagement by said piston member and adapted to shift said support means out of retaining relation to said head portions.

3. The well tool of claim 1 wherein said latch means includes inwardly biased spring fingers on said receptacle having enlarged head portions engageable-within an internal annular recess on said body member, and a support ring positioned behind said spring fingers for retaining said head portions engaged within said recess; said release means including an axially movable shifting member coupled to said support ring and extending upwardly to a location within the lower end of said receptacle, said shifting member being positioned for engagement by said piston member so that said piston member can cause said shiftin member to shift said support ring out from behind said latch rngers and enable said head portions to disengage from said recess. 

1. In a well tool for bridging a well bore: a body member carrying an inflatable packing element; a receptacle containing a fluent medium; passage means communicating said receptacle with the interior of said pacing means; pump means including a piston member movable downwardly in said receptacle for forcing said fluent medium through said passage means and into the interior of said packing means to inflate said packing means; latch means between said receptacle and said body member for releasably coupling said receptacle to said body member; and release means cooperating between said piston member and said latch means for releasing said latch means after said piston means has forced all said fluent medium from said receptacle.
 2. The well tool of claim 1 wherein said latch means includes laterally biased spring fingers on said receptacle having head portions engageable with an annular recess on said body member, and support means for retaining said head portion engaged with said recess; said release means including a shifting member coupled to said support means, said shifting member being positioned for engagement by said piston member and adapted to shift said support means out of retaining relation to said head portions.
 3. The well tool of claim 1 wherein said latch means includes inwardly biased spring fingers on said receptacle having enlarged head portions engageable within an internal annular recess on said body member, and a support ring positioned behind said spring fingers for retaining said head portions engaged within said recess; said release means including an axially movable shifting member coupled to said support ring and extending upwardly to a location within the lower end of said receptacle, said shifting member being positioned for engagement by said piston member so that said piston member can cause said shifting member to shift said support ring out from behind said latch fingers and enable said head portions to disengage from said recess. 